Updated: April 19, 2023 |
Test a character to see if it's alphanumeric
#include <ctype.h> int isalnum( int c );
libc
Use the -l c option to qcc to link against this library. This library is usually included automatically.
The isalnum() function tests if the argument c is an alphanumeric character (a to z, A to Z, or 0 to 9). An alphanumeric character is any character for which isalpha() or isdigit() is true.
Nonzero if c is a letter or decimal digit; otherwise, zero.
#include <stdio.h> #include <stdlib.h> #include <ctype.h> int main( void ) { if( isalnum( (unsigned)getchar() ) ) { printf( "That's alpha-numeric!\n" ); } return EXIT_SUCCESS; }
Safety: | |
---|---|
Cancellation point | No |
Interrupt handler | Yes |
Signal handler | Yes |
Thread | Yes |
The result is valid only for char arguments and EOF.